Are your API tests accurate?

becact · 03/06/2009, 10:29 PM

Took my water to the LFS which uses Salifert to test, just to check them against my API tests. My calcium read 420, while theirs read 370! Also not as bad, but still off was the alkalinity; mine read 8 KH and theirs read 9.2. On the plus side, my phosphate test was accurate at 0.

I thought API was supposed to be fairly accurate, not 50 points off on calc! I am now thinking of shelling out the $$$ for the Salifert calcium, alkalinity, and magnesium tests.

After each test on my API I wash the tubes out with RO/DI, and before each test I wash the tube and cap with the testing water. I am also careful to put the bottom of the meniscus right on the line. I think the problem is inaccurate droplet sizes.

Just mad because I just shelled out the money not too long ago for the API tests.

Make sure you verify your tests against a good test kit before relying on them!

kraze3 · 03/06/2009, 10:44 PM

WHt kind of tests is your LFS using?

I use API and never noticed a problem.

becact · 03/06/2009, 10:45 PM

They use Salifert.

tspors · 03/07/2009, 09:20 AM

Read this article it can explain many things testing is genralizations. There is very much merit in this article.

http://www.drsfostersmith.com/pic/ar...3&category=585

becact · 03/07/2009, 06:26 PM

I read the article, and understand error in testing. I just took Inorganic Chemistry I/II one semester ago, so I remember correct laboratory techniques. My test results are consistent, just not accurate compared to the Salifert.

I've read that the Salifert calcium tests can become inaccurate over time (due to the reagents contacting air). Anyone know if that's true?

will16 · 03/07/2009, 07:34 PM

I've tested my Salifert against my API and it was pretty close. Ca was like 420 on one and 440 on another. Alk would read like 8 on api and 8.8 on Salifert.

SCIFI_3D_zoo · 03/07/2009, 08:45 PM

I'm a big fan of Salifert kits. I just got burned too many times with API and RED SEA kits. Some things don't have to be as accurate. You can get away with Ca, Mg, etc. being a little off. It's a pretty wide safe range you can be in. But don't mess around with pH and ALK. You NEED to have a Pinpoint pH monitor. And a Salifert ALK. If you're gonna start messing with SPS's and whatnot you'll waste more money killing stuff than some good testing equipment will cost.

Tswifty · 03/07/2009, 11:43 PM

Quote:

Originally posted by will16
I've tested my Salifert against my API and it was pretty close. Ca was like 420 on one and 440 on another. Alk would read like 8 on api and 8.8 on Salifert.

+1

Klaus777 · 03/08/2009, 12:12 AM

Please check my thread on this same problem. Mine is more drastic in difference though.
http://www.reefcentral.com/forums/sh...readid=1590657

tspors · 03/08/2009, 08:16 AM

[QUOTE]Originally posted by becact
[B]I read the article, and understand error in testing. I just took Inorganic Chemistry I/II one semester ago, so I remember correct laboratory techniques. My test results are consistent, just not accurate compared to the Salifert.

Proud you took a class, Does not prove you, or the school boy at the LFS hit the drops just perfect. The point is what was said above most do not have to be perfect you are looking for ranges. Next class should be reality 101.

becact · 03/08/2009, 12:45 PM

[QUOTE]Originally posted by tspors
[B]

Quote:

Originally posted by becact
I read the article, and understand error in testing. I just took Inorganic Chemistry I/II one semester ago, so I remember correct laboratory techniques. My test results are consistent, just not accurate compared to the Salifert.

Proud you took a class, Does not prove you, or the school boy at the LFS hit the drops just perfect. The point is what was said above most do not have to be perfect you are looking for ranges. Next class should be reality 101.

What a douche!

jasonrp104 · 03/08/2009, 01:02 PM

mat167 · 03/08/2009, 05:20 PM

That was a good article, although error analysis is something that even introductory classes teach so I'm sure you've covered that well enough. I do believe, on the other hand, that the chemistry classes you've taken will help to a great extent, and they do show merit in your results.
Tspors, I have taken a few organic chem classes and can vouch that sloppy laboratory techniques guarantee a failure, so contrary to what has been mentioned, the courses do prove at least somewhat becact's competence. Unless he failed them of course

lol but I'm assuming he did decently well.

What is usually an issue with the API test kits, as I have found, is that many stores that carry them on the shelf have them there for some time. These kits are notorious for expiring quickly, so a few months on the shelf in the store is a big deal. Fresh kits will give you much better reading. I can honestly say this is the MOST encountered problem I've seen with API kits. I use API Alk and Ca with no problems. The only kits I wouldn't use are PO4 because of the measuring steps, and NO3 for low range measurements. I think the PO4 test's lowest measurement is about 0.5 ppm which is still really high for a reef tank. And the same goes for the NO3, although it's a little more forgivable. I use Salifert for NO3 and PO4.

You received a grade of "A" in Reality 101 :P

becact · 03/08/2009, 05:36 PM

Thanks mat167. Though Inorganic I/II certainly didn't make me a chem major, a lot of the focus in the lab portion of the course is on proper laboratory technique, so I'd like to think I can at least read a meniscus and hold a dropper bottle vertically, as well as not cross contaminate.

I can't find an expiration date on the API kit, but each bottle has a batch number. I think I'm going to call API's customer service on Monday and ask if they are still good. If they're expired, hopefully they will exchange the kit, or the petsmart will let me make a return. Thanks for that tip!

mat167 · 03/08/2009, 10:22 PM

No prob. I'm no chem major either, but the experience has helped a lot. Happy reefing.

03/06/2009, 10:29 PM	#1
becact Registered Member Join Date: Feb 2009 Location: South Dakota Posts: 550	Are your API tests accurate? Took my water to the LFS which uses Salifert to test, just to check them against my API tests. My calcium read 420, while theirs read 370! Also not as bad, but still off was the alkalinity; mine read 8 KH and theirs read 9.2. On the plus side, my phosphate test was accurate at 0. I thought API was supposed to be fairly accurate, not 50 points off on calc! I am now thinking of shelling out the $$$ for the Salifert calcium, alkalinity, and magnesium tests. After each test on my API I wash the tubes out with RO/DI, and before each test I wash the tube and cap with the testing water. I am also careful to put the bottom of the meniscus right on the line. I think the problem is inaccurate droplet sizes. Just mad because I just shelled out the money not too long ago for the API tests. Make sure you verify your tests against a good test kit before relying on them!

03/07/2009, 09:20 AM	#4
tspors Registered Member Join Date: Sep 2007 Location: Appleton, WI. USA Posts: 774	Read this article it can explain many things testing is genralizations. There is very much merit in this article. http://www.drsfostersmith.com/pic/ar...3&category=585 __________________ Everything is Good with Moderation. Current Tank Info: 150 Gal Oceanic, 30g Sump, Gen-X PCX-150 2250 gph, Red Sea Clasic Turbo Skimmer, 18w Turbo Twist UV, Ocean Clear Filter w/live rock, Several Buckets,

03/07/2009, 08:45 PM	#7
SCIFI_3D_zoo Registered Member Join Date: Nov 2005 Location: Sebring, Florida Posts: 1,072	I'm a big fan of Salifert kits. I just got burned too many times with API and RED SEA kits. Some things don't have to be as accurate. You can get away with Ca, Mg, etc. being a little off. It's a pretty wide safe range you can be in. But don't mess around with pH and ALK. You NEED to have a Pinpoint pH monitor. And a Salifert ALK. If you're gonna start messing with SPS's and whatnot you'll waste more money killing stuff than some good testing equipment will cost. __________________ The Key to immortality is to first live a life worth living.... BRUCE LEE Current Tank Info: 90g Reef(no SPS b/c of AquaC skimmer) Pacific Blue Tang, Maroon Clown(hosting Finger Leather), Mystery Wrasse(who's location is a mystery), Coral Beauty, Mandarin. AquaC EV240, JBJ ATO, KALK top-off, Prodibio

03/08/2009, 08:16 AM	#10
tspors Registered Member Join Date: Sep 2007 Location: Appleton, WI. USA Posts: 774	[QUOTE]Originally posted by becact [B]I read the article, and understand error in testing. I just took Inorganic Chemistry I/II one semester ago, so I remember correct laboratory techniques. My test results are consistent, just not accurate compared to the Salifert. Proud you took a class, Does not prove you, or the school boy at the LFS hit the drops just perfect. The point is what was said above most do not have to be perfect you are looking for ranges. Next class should be reality 101. __________________ Everything is Good with Moderation. Current Tank Info: 150 Gal Oceanic, 30g Sump, Gen-X PCX-150 2250 gph, Red Sea Clasic Turbo Skimmer, 18w Turbo Twist UV, Ocean Clear Filter w/live rock, Several Buckets,

03/06/2009, 10:44 PM	#2
kraze3 Registered Member Join Date: Jan 2006 Location: RI Posts: 2,373	WHt kind of tests is your LFS using? I use API and never noticed a problem.

03/06/2009, 10:45 PM	#3
becact Registered Member Join Date: Feb 2009 Location: South Dakota Posts: 550	They use Salifert.

03/07/2009, 06:26 PM	#5
becact Registered Member Join Date: Feb 2009 Location: South Dakota Posts: 550	I read the article, and understand error in testing. I just took Inorganic Chemistry I/II one semester ago, so I remember correct laboratory techniques. My test results are consistent, just not accurate compared to the Salifert. I've read that the Salifert calcium tests can become inaccurate over time (due to the reagents contacting air). Anyone know if that's true?

03/07/2009, 07:34 PM	#6
will16 Registered Member Join Date: Jan 2008 Location: Northern NJ Posts: 1,812	I've tested my Salifert against my API and it was pretty close. Ca was like 420 on one and 440 on another. Alk would read like 8 on api and 8.8 on Salifert.

03/08/2009, 12:12 AM	#9
Klaus777 Registered Member Join Date: Jul 2008 Location: Kitchener, ontario Posts: 244	Please check my thread on this same problem. Mine is more drastic in difference though. http://www.reefcentral.com/forums/sh...readid=1590657

03/08/2009, 01:02 PM	#12
jasonrp104 Registered Member Join Date: Nov 2008 Location: vt Posts: 1,113

03/08/2009, 05:20 PM	#13
mat167 Registered Member Join Date: Apr 2008 Location: Montreal, South-Shore Posts: 473	That was a good article, although error analysis is something that even introductory classes teach so I'm sure you've covered that well enough. I do believe, on the other hand, that the chemistry classes you've taken will help to a great extent, and they do show merit in your results. Tspors, I have taken a few organic chem classes and can vouch that sloppy laboratory techniques guarantee a failure, so contrary to what has been mentioned, the courses do prove at least somewhat becact's competence. Unless he failed them of course lol but I'm assuming he did decently well. What is usually an issue with the API test kits, as I have found, is that many stores that carry them on the shelf have them there for some time. These kits are notorious for expiring quickly, so a few months on the shelf in the store is a big deal. Fresh kits will give you much better reading. I can honestly say this is the MOST encountered problem I've seen with API kits. I use API Alk and Ca with no problems. The only kits I wouldn't use are PO4 because of the measuring steps, and NO3 for low range measurements. I think the PO4 test's lowest measurement is about 0.5 ppm which is still really high for a reef tank. And the same goes for the NO3, although it's a little more forgivable. I use Salifert for NO3 and PO4. You received a grade of "A" in Reality 101 :P

03/08/2009, 05:36 PM	#14
becact Registered Member Join Date: Feb 2009 Location: South Dakota Posts: 550	Thanks mat167. Though Inorganic I/II certainly didn't make me a chem major, a lot of the focus in the lab portion of the course is on proper laboratory technique, so I'd like to think I can at least read a meniscus and hold a dropper bottle vertically, as well as not cross contaminate. I can't find an expiration date on the API kit, but each bottle has a batch number. I think I'm going to call API's customer service on Monday and ask if they are still good. If they're expired, hopefully they will exchange the kit, or the petsmart will let me make a return. Thanks for that tip!

03/08/2009, 10:22 PM	#15
mat167 Registered Member Join Date: Apr 2008 Location: Montreal, South-Shore Posts: 473	No prob. I'm no chem major either, but the experience has helped a lot. Happy reefing.